Pressure foot for sewing machines

ABSTRACT

This invention relates to a pressure foot for sewing machines having a pressure foot bar. Said pressure foot for sewing machines comprises a shank detachably connectable to the sewing machine pressure foot bar, a lever pivotally connected to a pair of lugs, a wire connected at its base to the lower end of said lever and movably extending through a longitudinal bore so that its forward end portion projects into a transverse slot, means normally urging said wire to close at its front end portion the open side of said transverse slot, and a pressure shoe having a pair of supports extending along opposite sides of the upper surface of the shoe for supporting a shaft extending transversely of the shoe and adapted to be received in said transverse slot formed in said shank and retained therein by the forward end portion of the wire closing the open side of the transverse slot. Said shank is formed with a vertical groove at one side thereof for receiving the pressure foot bar therein and having said transverse slot formed at the bottom to extend from side to side of the shank and a plurality of lugs extending rearwardly from the back of the shank, and the shank is further formed with a longitudinal bore extending forwardly from the back of the shank and opening in said slot.

United States Patent [191 Niino Apr. 2, 1974 PRESSURE FOOT FOR SEWING MACHINES [75] Inventor:

[73] Assignee: Koshin Seimitsu Kikai Kabushiki Kaisha, Tokyo, Japan 22 Filed: Mar.26, 1973 21 App]. No.: 344,923

Kumao Niino, Tokyo, Japan [30] Foreign Application Priority Data Primary Examiner-Richard J. Scanlan, Jr. Attorney, Agent, or FirmStevens, Davis, Miller &

Mosher [57] ABSTRACT This invention relates to a pressure foot for sewing machines having a pressure foot bar.

Said pressure foot for sewing machines comprises a shank detachably connectable to the sewing machine pressure foot bar, a lever pivotally connected to a pair of lugs, a wire connected at its base to the lower end of said lever and movably extending through a longitudinal bore so that its forward .end portion projects into a transverse slot, means normally urging said wire to close at its front end portion the open side of said transverse slot, and a pressure shoe having a pair of supports extending along opposite sides of the upper surface of the shoe for supporting a shaft extending transversely of the shoe and adapted to be received in said transverse slot formed in said shank and retained therein by'the forward end portion of the wire closing the open side of the transverse slot.

Said shank is formed with a vertical groove at one side thereof for receiving the pressure foot bar therein and having said transverse slot formed at the bottom to extend from side to side of the shank and a plurality of lugs extending rearwardly from the back of the shank, and the shank is further formed with a longitudinal bore extending forwardly from the back of the shank and opening in said slot.

4 Claims, 17 Drawing Figures PATENTEU APR 2 i9 4 SHEU '1 OF 2 FIG. 1a

' PRESSURE FOOT FOR SEWING MACHINES This invention relates to a pressure foot for sewing machines.

In one type of pressure foot for sewing machines known in the art, a shank a and a pressure shoe b are formed separately in two pieces for detachable connection as shown in FIG. 1 (a) and FIG. 1 (b). Means for connecting the two elements together comprises a slot formed at the bottom of the shank a, a pair of supports 14, 14 extending along opposite sides of the upper surface of the pressure shoe b, and a shaft 15 mounted on the supports 14, 14. In effecting connection, the shaft 15 is first inserted in the slot 5 and then the latter is closed. Means for closing the open side of the slot 5 comprises a clearance c formed between the bottom of the shank a and the top of the pressure shoe b, and a leaf spring 16 extending along the back of the shank a, bent at right angles to the back of the shank a and firmly secured at its upper end to the shank a. The leaf spring 16 is pulled as shown in a dash-and-dot line in FIG. 1 (a) by means of a lever 18 to open the .closed slot 5, or the lever 18 is pivotally connected to the shank a as shown in FIG. 1 (b) and formed at its forward end with a claw-like portion 18 which is urged by the biasing force of a spring to press the shaft against the shank a at all times. The formation of the clearance c calls for precise machining and thus renders the pressure foot of this type unsuitable for practical use because the production is time consuming and production cost is high.

The present invention has as its object the provision of a pressure foot for sewing machines which obviates the aforementioned disadvantages of the prior art.

According to the invention, there is provided a pressure foot for sewing machines having a pressure foot bar, comprising a shank detachably connectable to the sewing machine pressure foot bar, the shank being formed with a vertical groove at one side thereof for receiving the pressure foot bar therein and having a transverse slot formed at the bottom to extend from side to side of the shank and a plurality of lugs extending rearwardly from the back of the shank, the shank being further formed with a longitudinal bore extending forwardly from the back of the shank and opening in the transverse slot, a lever pivotally connected to said pair of lugs, a wire connected at its base to the lower end of the lever and movably extending through the longitudinal bore so that its forward end portion projects into the transverse slot, means normally urging the wire to close at its forward end portion the open side of the transverse slot, and a pressure shoe having a pair of supports extending along opposite sides of the upper surface of the shoe for supporting a shaft extending transversely of the shoe and adapted to be received in the transverse slot formed in the shank and retained therein by the forward end portion of the wire closing the open side of the transverse slot.

Additional and other objects as well as features and advantages of the invention will become evident from the description set forth hereinafter when considered in conjunction with the accompanying drawings, in which:

FIG. 1 (a) and FIG. 1 (b) are vertical sectional views of a pressure foot of the prior art for sewing machines;

FIG. 2 is a side view of the pressure foot for sewing machines comprising one embodiment of the invention;

FIG. 3 is a plan view of the pressure shoe shown in FIG. 2;

FIG. 4 is a side view of the shank of the pressure foot shown in FIG. 2;

FIG. 5 is a rear view of the shank;

FIG. 6 is an exploded view of the shank;

FIG. 7 is a side view of the essential portions of the shank of the pressure foot comprising another embodiment of the invention with certain parts being cut away;

FIG. 8 (a) and FIG. 8 (b) are a perspective view and a side view respectively of the wire of the pressure foot shown in FIG. 4;

FIG. 9 is an enlarged perspective view of the essential portions of the shank of another form;

FIG. 10 (a), FIG. 10 (b) and FIG. 10 (c) are views in explanation of various forms of the bore formed in the shank;

FIG. 11 is a side view of the pressure foot comprising another embodiment of the invention;

FIG. 12 is an enlarged side view of the pressure foot shown in FIG. 11; and

FIG. 13 is an enlarged side view of the wire of another form.

In FIG. 2 to FIG. 6, the pressure foot for sewing machines according to the invention comprises a shank a and a pressure shoe b. The shank a comprises a vertical portion 1 to be connected to a pressure foot bar of the sewing machine (not shown), and a horizontal portion 2 to be connected to the pressure shoe b. A longitudinal groove 3 is formed at one side of the vertical portion 1 for receiving the pressure foot bar therein, and at its back with a plurality of lugs 4 which extend rearwardly in parallel relationship. The horizontal portion 2 is formed with a slot 5 extending from side to side, and a bore 6 extending forwardly from the back of the horizontal portion 2 to open in the slot 5.

A lever 7 having an upper end portion 7a and a lower connecting portion 7b formed therein with a plurality of openings 8 and 9 is pivotally connected to the lugs 4, 4 by means of a pin 11 inserted in the upper opening 8 and openings formed in the lugs 4, 4. The lever 7 is urged by the biasing force of a wire spring 10 to move clockwise in FIG. 2. A wire 13 is connected at its base to the lever 7 by means of a rivet 12 inserted in the lower opening 9, and extends through the bore 6, so that its front end portion projects into the slot 5 and closes the open side of the slot 5. Thus, by pushing and moving the upper end portion 7a of the lever counter clockwise in FIG. 2 or toward the vertical portion 1 of the shank a against the biasing force of the spring 10, the wire 13 can be moved rearwardly in the slot 5 and its forward end portion is withdrawn into the slot 5, thereby opening the slot 5.

As shown in FIG. 2 and FIG. 3, the pressure shoe b is formed with a pair of supports l4, 14 extending along opposite sides of its upper surface for supporting a shaft 15 which is disposed across the width of the pressure shoe b. By closing the open side of the slot 5 by the forward end portion of the wire 13 after the shaft 15 is fitted in the slot 5 formed in the horizontal portion 2 of the shank' a, it is possible to retain the shaft 15 in the slot 5 and keep the shank a and pressure shoe b connected to each other.

The interconnected shank a and pressure shoe b can be detached from each other by pushing and moving.

the upper end portion 7a of the lever 7 toward the vertical portion 1 of the shank a to withdraw the forward end portion of the wire 13 into the bore 6. If the shank a is moved upwardly at this time, it can readily be detached from the pressure shoe b.

From the foregoing description, it will be appreciated that the shank a can readily be connected to and disconnected from the pressure shoe b by means of the wire 13 extending through the bore 6 of the shank a. The arrangement permits the shank and pressure shoe to be fabricated readily and quickly, because there is no need to form by precision machining a clearance between them as is required in pressure foot of the prior art.

FIG. 7 and FIG. 8 show another embodiment of the invention in which the forward end portion 13a of the wire 13 is formed with a downwardly inwardly inclined end surface 13b. If the forward end portion 13a of the wire 13 is brought into engagement with the shaft 15 and the shank a is pushed downwardly. while the forward end portion 13a is in a position to close the open side of the slot 5, then the inclined end surface 13b of the wire 13 is pushed and guided in sliding motion by the periphery of the shaft 15 so that the forward end portion 13a is withdrawn into the bore 6, thereby permitting the shaft 15 to move into the slot 5. The forward end portion 13a of the wire 13 loses no time in being restored to its operative position in which it closes the open side of the slot 5, thereby precluding the dislodging of the shaft 15 from the slot 5.

FIG. 9 to FIG. 10 (a) to FIG. 10 show another embodiment of the invention. In this embodiment, the bore 6 is formed between one side of the horizontal portion 2 of the shank a and a guide 19 secured to the one side of the horizontal portion 2, instead of in the horizontal portion 2 to extend longitudinally thereof as in the case with the embodiments shown and described above. This arrangement permits the thickness of the shank a to be reduced.

Alternatively, the bore 6 may be formed in the guide 19 by bending the lower end portion of the guide 19, or the bore 6 may be disposed on the underside of the horizontal portion 2 of the shank a.

FIG. 11 to FIG. 13 show still another embodiment of the invention. As shown, the slot has a depth which is greater than the diameter of the shaft 15 so that the latter may be disposed in a bottom portion 5a of the slot 5. Inclined portions 0, and 0 are formed in the forward and rearward sections of the bottom of the horizontal portion 2 so that a clearance may be formed between the forward and rearward sections of edges 5b and 5c of the slot 5 and the upper surface of the pressure shoe b when the edges 5b and 5c are brought into contact with the upper surface of the pressure shoe b. The bore 6 has a diameter which is greater than the diameter of the wire 13 so that there may be a clearance between them.

As shown in FIG. 13, a spring may be mounted on the rivet l2 on which the wire 13 is pivoted, so as to urge the forward end portion 13a of the wire 13 to move upwardly by the biasing force of the spring 20. In this embodiment, the shaft 15 is urged to move upwardly into pressing engagement with the bottom portion 5a of the slot 5 by the forward end portion 130 of the wire 13 urged to move upwardly by the biasing force of the spring 20, when the shank a and pressure shoe b are interconnected. This permits the edges 5b and 5c of the slot 5 to be brought into contact with the upper surface of the pressure shoe b so as to thereby preclude the oscillating movement of the pressure shoe b with respect to the shank a when the pressure foot is moved upwardly. This eliminates the disadvantage of the sewing needle being damaged by striking the neighborhood of a needle hole 21 formed in the pressure shoe b, even if the needle hole 21 is small in dimension.

The provision of the inclined portions 0 and 0 in the bottom of the horizontal portion 2 of the shank a enables a sewing operation to be performed smoothly and positively, because the pressure shoe b constructed as aforementioned can accommodate irregularlties on the surface of the cloth handled.

What I Claim Is:

1. A pressure foot for sewing machines having a pressure foot bar, comprising a shank detachably connectable to the sewing machine pressure foot bar, said shank being formed with a vertical groove at one side thereof for receiving the pressure foot bar therein and having a transverse slot formed at the bottom to extend from side to side of the shank and a plurality of lugs extending rearwardly from the back of the shank, the shank being further formed with a longitudinal bore extending forwardly from the back of the shank and opening in said slot, a lever pivotally connected to said pair of lugs, a wire connected at its base to the lower end of said lever and movably extending through said longitudinal bore so that its forward end portion projects into said transverse slot, means normally urging said wire to close at its front end portion the open side of said transverse slot, and a pressure shoe having a pair of supports extending along opposite sides of the upper surface of the shoe for supporting a shaft extending transversely of the shoe and adapted to be received in said transverse slot formed in said shank and retained therein by the forward end portion of the wire closing the open side of the transverse slot.

2. A pressure foot according to claim 1 wherein said wire is formed at its forward end with a downwardly inwardly inclined end surface.

3. A pressure foot according to claim 1 wherein said bore is formed by one side of the lower portion of the shank and a guide connected to said one side of the shank.

4. A pressure foot according to claim 1 wherein said slot has a depth which is greater than the diameter of said shaft, said bore has a diameter greater than that of said wire, and inclined portions are formed in sections of the bottom of the shank disposed forwardly and rearwardly of the slot so that a clearance may be formed between the sections of the bottom of the shank disposed forwardly and rearwardly of the slot and the upper surface of the pressure shoe.

i l 4 I8 i 

1. A pressure foot for sewing machines having a pressure foot bar, comprising a shank detachable connectable to the sewing machine pressure foot bar, said shank being formed with a vertical groove at one side thereof for receiving the pressure foot bar therein and having a transverse slot formed at the bottom to extend from side to side of the shank and a plurality of lugs extending rearwardly from the back of the shank, the shank being further formed with a longitudinal bore extending forwardly from the back of the shank and opening in said slot, a lever pivotally connected to said pair of lugs, a wire connected at its base to the lower end of said lever and movably extending through said longitudinal bore so that its forward end portion projects into said transverse slot, means normally urging said wire to close at its front end portion the open side of said transverse slot, and a pressure shoe having a pair of supports extending along opposite sides of the upper surface of the shoe for supporting a shaft extending transversely of the shoe and adapted to be received in said transverse slot formed in said shank and retained therein by the forward end portion of the wire closing the open side of the transverse slot.
 2. A pressure foot according to claim 1 wherein said wire is formed at its forward end with a downwardly inwardly inclined end surface.
 3. A pressure foot according to claim 1 wherein said bore is formed by one side of the lower portion of the shank and a guide connected to said one side of the shank.
 4. A pressure foot according to claim 1 wherein said slot has a depth which is greater than the diameter of said shaft, said bore has a diameter greater than that of said wire, and inclined portions are formed in sections of the bottom of the shank disposed forwardly and rearwardly of the slot so that a clearance may be formed between the sections of the bottom of the shank disposed forwardly and rearwardly of the slot and the upper surface of the pressure shoe. 